Incineration



G. R. LEWERS Mmh 14, 1939.

INC INERAT ION Filed Oct. l5, 1936 H///////////////// 0% M 7 /M/m w wk amw\ 00 /f a mw im 0 mmx w, ww m dm INVENTOR y George F?. Len/ers BY C?AWA- JCL ATTORNEY Patented Mar. 14, 1939 UNITED STATES PATENT OFFICEINCINERATION Application October 15, 1936, Serial No. 105,695

5 Claims.

My invention relates to the incineration or burning of materialcontaining moisture and volatile material, and more particularly to thedisposal in this way of material such as sewage 5 sludge, sewagescreenings, garbage and municipal waste in general.

The principal objects of the invention are to provide a novel andadvantageous apparatus and a novel and advantageous process for dryingand burning material, particularly material of the general typespecified.

I-Ieretofore it has been proposed to dry material in a multiple-hearthVdryer or furnace and then to burn the dried material in a refuseincinerator, of the Decarie type for example, and to conduct hot wastegases from the incinerator through the multiple-hearth dryer in contactwith the material on the hearths for heating and drying purposes andthen to return the gases to a hot part of the incinerator, and also torecover waste heat by use of heat exchangers exterior to the dryingfurnace.

In carrying out my invention, heat exchangers exterior to the burningfurnace may either be eliminated or may be used in a different way. Asan illustration, I propose to use a Decarie incinerator adjacent towhich is a multiple-hearth dryer or drying furnace which is similar tomulti# ple-hearth roasting furnaces used in the metallurgical industryexcept that use is made of hollow hearths of heat conducting material,such as steel, cast iron or other suitable material. Such hollow hearthsor drying trays may be in the form of hollow annular chambers throughwhich 35 all or part of the hot gases from the incinerator may bepassed, either in multiple, or in series,'or

partly in multiple and partly in series. From the hollow hearths thegases may be passed to a heat saving device, such as a heat exchanger,and eventually to a stack. The temperature of the gases entering thedryer may be reduced by admitting cold air.

Heated air from a heat exchanger may be passed over the material beingdried in the dryer and the resulting moisture laden gas may then beconducted from the dryer to the hot zone of the incinerator where odorsare destroyed'and the resulting gases mixed with gases produced in theincinerator are passed to the stack. If the temperatures within thedryer are controlled to a range wherein noxious odors are not producedin the drying operation, the moisture laden gases may be dischargeddirectly to the stack instead of being passed to the incinerator for theelimination 55` of odor.

vAI second heat exchanger may be used '(Cl. 11o-8) so that the hot gasesfrom the incinerator before entering the drying hearths or trays willheat fresh air which may be used in connection with the dryingoperation.

vOther objects, lfeatures and advantages will appear upon considerationof the following description and of the drawing in whichthe figure is asectional elevation of an approved form of the apparatus. l

Referring to the drawing, the apparatus comprises a multiple-hearthdryer or drying furnace III and a basket-grate furnace II of the Decarietype. The dryer I may comprise a top I2, hearths I3, I4, I and I6, whichhearth I6 serves as the bottom of the dryer or drying furnace Ill. Inorder to promote drying of the material under treatment, the top I2 andthe hearths I3, I4, I5 and I6 may be hollow and made of heat conductingmaterial such as steel or cast iron. The said top and hearths are spacedapart vertically and supported in a peripheral wall I'I. The furnace maybe provided above the top I2 with any suitable insulating material suchas sand I8.

The material to be dried may be introduced into the top of the dryerthrough a hopper I9 and a chute 20 extending through the top I2 andprovided with a pivoted door 2| normally held in closed position by aweighted arm 22 but arranged to open when a sufcient quantity ofmaterial has accumulated thereon. The material thus introduced into theuppermost compartment or zone will fall upon the hearth I3. In ordertosubject the material to as much contact as possible with the air andgases passing through the dryer and to enable the material to passdownwardly through and out of the dryer, the hearths I3 and I5 areprovided with central discharge openings or outlets 23 and 24respectively and hearths I4 and I6 are provided with peripheral outlets25 and 26.

The material may be worked tol the outlets of the various hearths bysuitable rabbling means which may comprise a vertical shaft 21, passingfreely through the central outlets 23 and 24 of the hearths I3 and I5and through gas seals at the hearths I4 and I6 and at the top I2, andrabbling devices extending over said hearths from the vertical shaft andconsisting of arms 28 and blades 29 so inclined at each hearth as towork the material on the hearths to the corresponding outlets. The shaftZ'I'may be driven by suitable means such as a bev-el gear 30 and apulley 32 secured to gear 3| and driven from any suitable source ofpower. When the material on the lowermost hearth or bottom I6 is Workedoutwardly and around to the outlet 26, it drops into a chute 33 on apivoted door 34 normally held in closed position by a suitable Weightedarm 35. When a sufficient amount of material has accumulated thereon,the door 34 swings open and dried material is discharged from the dryer.

The dried material discharged from the chute 33 at the bottom of thedryer may drop into a hopper 36 at the top of a chute 31 extendingthrough the top 38a of the furnace l I. 31 may normally be closed bysuitable means such as two pivoted gates or doors 39 normally held inclosed position by weighted arms 46.

Material entering the incinerator I i through the chute 31 passes into aburning chamber 38a and falls into a water-cooled basket grate 39 abovea re or burning grate 46. 'Ihe gases of combustion rising from materialburning on the grate 46 pass around and to some extentthrough thematerial in the basket grate 39 and dry and partially burn it so that incourse of time the materialwill drop through the basket grate and fallon the grate 4B. The material thus falling on the grate 4D may besufficient to maintain the operation of the furnace, but, if the amountis insuicient, auxiliary fuel may be introduced in any suitable manner,for example, through a port 4| normally closed by a door 42 or by meansof an oil burner. Air may be supplied beneath the grate 40 in anysuitable manner, for example, through a duct or pipe 43. The hot gasesfrom the burning chamber 38 pass upwardly over a bridge wall 44 into theupper part of a combustion chamber 45 in which the combustible gases arefinally burned. From the lower partY of the combustion chamber 45 thehot gases pass through a flue 46 to a stack 41, the ow of gases throughthe flue 4S being controlled by suitable means such as a damper 46movable vertically and counterbalanced by a weight 49 connected with thedamper 48 by means of a flexible member 56 passing over a pulley 56a.

The hollow hearths of the dryer I9 may be heated by passing therethroughhot gases of combustion from the incinerator preferably from thecombustion chamber 45. To this end there is provided a manifold 50hconnected with the combustion chamber 45 and connected through branchesor ducts 5|, 52, 53, 54 and 55 with the hollow hearths I2, I3, I4, I5and I6, respectively. The same hearths are also connected by ducts 56,51, 58, 59 and 66 with a manifold 6| connecting with a duct 62 throughwhich the hot gases are drawn by means of a large fan 63. With thisarrangement hot gases from the combustion chamber 45 of the incineratorwill be drawn through the hollow hearths and discharged from theapparatus in any suitable manner. By providing the ducts 5|, 52, 53, 54and 55 with dampers 64, 65, 66, 61, and 68 respectively, and bypro-viding the ducts 56, 51 58, 59 and 66 with dampers 69, 1U, 1|, 12and 13v respectively any one of the hollow hearths may be shut oir andthe hot gasesV it is made possible to pass the gases through the hollowhearths either in multiple or in series.

It is also desirable to supply preheated air to the various compartmentsof the dryer l!) and to the incinerator I I below the grate 46. To thisVend there may be provided a fan 18 forcing air The chute through a duct19 surrounding the outlet duct 62 for the hot gases and cooperatingtherewith to form a heat exchanger 89 whereby preheated air is suppliedto a manifold 8| having branches or ducts 82, 83, 84 and 85 as well asthe duct 43 leading to the incinerator II which ducts are controlledVrespectively by dampers 86, 81, 88 and 89. After passing through thecompartments above the corresponding hollow hearths, the air laden withmoistureand vapors passes out of the dryer into branches or ducts 99,9|, 92 and 93 controlled by dampers 94, 95, S6 and 91. From the lducts9U to 98 inclusive, the air and vapors pass to a manifold 98 connectedby a branch 99 with the burning chamber of the incinerator I I and by abranch |953 with the flue 46 leading to the stack 41, these branches 99and |69 being controlled by dampers 16| and |92 respectively.

If desired, a heat interchanger |03 may be provided along the manifold50h and air may be forced therethrough by means of a fan |04 to a duct|65 to deliver the preheated air to any desired point in the apparatus,for example, to the manifold 8|.

During the normal operation of the apparatus, material which may besewage sludge, is supplied to the hopper I9 and is fed by gravity pastthe pivoted door 2| and through the chute 20 into the upper compartmentwhere it falls on the hearth i3. By the action of the rabbling means,the material is in general kept in a single layer on each hearth and isfed by the blades 29 inwardly to the central openings 23 and 24 ofhearths I3 and I5 and outwardly to the peripheral openings 25 and 26 inthe hearths I4 and I6, thus being fed gradually downwardly to the bottomof the dryer I5 to the outlet 26.

From the outlet 26 of the dryer I6, the dried l material is fedintermittently into the burning or furnace chamber 58a of theincinerator ||V where it is received in the basket grate l39. Here it issubjected to hot gases of combustion resulting from the burning ofmaterial on the fire grate 49 and after further drying and more or lesscharring and burning, falls to the grate 4U and serves as fuel fordrying and burning the other material deposited in basket grate 39. Thegases of combustion pass over the bridge wall 44 into the gas combustionchamber 45 and then through the flue 46 to the stack which provides yanatural draft which can be regulated by the damper 48.

Part of the drying action in the dryer I8 may be obtained by taking hotgases of combustion from the incinerator, preferably from the combustionchamber 45, and passing them through the manifold 50h and the branches5|, 52, 53 54 and 55into the hollow trays I3, I4, I 5 and I6, and out ofthe hollow hearthsjthrough ducts 56, 51, 58, 59 and 59 to a manifold 63|connected to a discharge pipe or duct 82 provided with the suction fan63. Obviously the hot gases serve to heat the hollow hearths and to heatand dry the material on the varioushearths. By means of the dampers inthe manifolds and the branches connected therewith, the flow of gasesthrough the hollow hearths may be controlled substantially as requiredor desired. Ordinarily the gases flow through the hearths in multiple,but by shifting the dampers 14, 15, 16 and 11, the gases may flowthrough the hollow hearths in series.

The fan 1;8 serves to supply air to the heat ex,- changer and therefromto the manifold 8|.

From the, manifold 8|, the preheated air passes,

through the duct 43-to a position belowv thevrve grate 4U, and throughthe ducts 82, 83, 84 and 85 to the compartments over the hearths I3, I4,I and I6 respectively. From these compartments the air passes outthrough branches or ducts 90, 9|, 92 and 93 to a manifold 98, and fromthe manifold 98 the air and vapors taken up thereby pass to the furnacechamber 38a, or to the flue 46, or partly to one and partly to the otheras determined by the dampers IGI and I02.

By use of a heat interchanger |03, heat may be taken from the hot gasesin manifold 501)I and at the same time air may be preheated for usewhere desired, for example in the furnace chamber 38a.

It will be seen that very effective and-economical drying and burningmay be effected by use of the apparatus of the present invention.

Although the inlets and outlets of 'the hollow hearths are illustratedas being at opposite sides of the dryer, they may be at the same side ofthe dryer, the inlet and outlet for each hollow hearth being at oppositesides of a radial partition, as disclosed in my copending application,Serial No. 103,875, filed October 3, 1936.

It should be understood that Various changes may be made and Variousfeatures used without others without departing from the true scope andspirit of the invention.

Having thus described my invention, I claim:

1. In combination, a multiple-hearth dryer dlvided into compartments byvertically spaced hollow trays serving as the top and the hearths andhaving means for moving material introduced at the top downwardly fromtray to tray and discharging it at the bottom, an incinerator receivingmaterial from the dryer and comprising a furnace chamber and acombustion chamber connected at its upper part with the upper part ofthe furnace chamber, means for passing hot gases from said combustionchamber to each of said hollow trays, a heat exchanger connected withall of said hollow trays to receive gases therefrom, means for drawingthe hot gases from said trays through said heat exchanger, means forintroducing air preheated in said heat exchanger into each of thecompartments between said trays and into said furnace chamber andwithdrawing air and vapors from each of said compartments anddischarging them into said furnace chamber.

2. In combination, a multiple-hearth dryer dlvided into compartments byvertically spaced hollow trays serving as the top and the hearths andhaving means for moving material introduced at the top downwardly fromtray to tray and discharging it at the bottom, an incinerator receivingmaterial from the dryer and comprising a furnace chamber and acombustion chamber connected at its upper part with the upper part ofthe furnace chamber, a flue receiving hot gases from the lower part ofthe combustion chamber, means for passing hot gases from saidcombustion'chamber to each of said hollow trays, a heat exchangerconnected with all of said hollow trays to receive gases therefrom,means for drawing the hot gases from each of said trays through saidheat exchanger, means for introducing air preheated in said heatexchanger into each of th'e compartments between said trays and intosaid furnace chamber and withdrawing air and vapors from each of saidcompartments and means for discharging air and vapors from thecompartments into said flue.

3. In combination, a multiple-hearth dryer comprising compartmentsbetween vertically spaced hollow trays serving as the top and thehearths and means for moving material introduced at the top downwardlyfrom tray to tray the furnace chamber, a discharge flue connected withthe lower part of the combustion chamber,

a hot-gas manifold connected at its lower end to said combustionchamber, branch ducts vconnecting the hot gas manifold withcorresponding hollow hearths, a discharge manifold connected with saidtrays to receive hot gases therefrom, dampers for said branch ducts andmanifolds whereby the hot gases may be caused to pass through saidhollow trays in parallel or in series, a heat exchanger connected withthe discharge manifold and heated by the hot gases from the same, meansfor drawing the hot gases through said hollow trays and said heatexchanger, means for passing air through said heat exchanger to beheated therein, an air-supply manifold receiving heated air from saidheat exchanger, branch ducts supplying the preheated air from saidairsupply manifold to said compartments between the hollow trays and tosaid furnace chamber, an air discharge manifold, branch ducts connectingsaid compartments with said air-discharge manifold, air-control damperswhereby the preheated air may be passed through said compartments inparallel or in series, branch ducts connecting said air-dischargemanifold with said furnace chamber and said flue respectively, anddampers for controlling the flow of air through said last mentionedbranch ducts.

4. In combination, a multiple-hearth dryer comprising compartmentsbetween vertically spaced hollow trays serving as the top and thehearths and means for moving material introduced at the top downwardlyfrom tray to tray and discharging it at the bottom, an incineratorcomprising a furnace chamber receiving material from the dryer and acombustion chamber connected at its upper part with the upper part ofthe furnace chamber, a discharge flue connected with the lower part ofthe combustion chamber, a hot-gas manifold connected at its lower end tosaid combustion chamber, branch ducts connecting the hot gas manifoldwith corresponding hollow hearths, a discharge manifold connected withsaid trays to receive hot gases therefrom, a heat exchanger heated bythe hot gases from the combustion chamber, means for drawing the hotgases through said hollow trays and manifolds, means for passing airthrough said heat exchanger to be heated therein, an air-supply manifoldreceiving heated air from said heat exchanger, branch ducts supplyingthe preheated air to said compartments between the hollow trays and tosaid furnace chamber, an air discharge manifold, branch ducts connectingsaid compartments with said air-discharge manifold, branch ductsconnecting said air-discharge manifold with said furnace chamber andsaid ue respectively, and dampers for controlling the flow of airthrough said last mentioned branch ducts.

5. In combination, a multiple-hearth dryer comprising compartmentsbetween vertically spaced hollow trays serving as the top and thehearths and means for moving material introduced at the top downwardlyfrom tray to tray and discharging it at the bottom, an incineratorcomprising a furnace chamber receiving material from the dryer and acombustion chamber connected at its upper part with the upper part ofthe furnace chamber, a hot-gas manifold connected at its lower end tosaid combustion chamber, branch ducts connecting the hotgasmanifold withcorresponding hollow hearths, a discharge manifold connected with saidtrays to receive hot gases therefrom, a heat exchanger connected bythehot gases from the combustion chamber, means for drawing the hot gasesthrough said hollow trays and manifolds, means for passing air throughsaid heat exchanger to be heated therein, an air-supply manifoldreceiving heated air from said heat exchanger, branch ducts supplyingthe preheated air to said compartments between the hollow trays, an airdischarge manifold, branch ducts connecting said compartments with saidair-discharge manifold, and means for conducting air from saidair-discharge manifold to said furnace chamber.

GEORGE R. LEWERS.

